Effects Of Exercise Intensity On Diastolic Function In Breast Cancer Patients Undergoing Chemotherapy

Breast cancer (BC) chemotherapy is associated with diastolic dysfunction. Exercise improves diastolic function in patients with heart failure, but its effects have yet to be demonstrated in patients receiving chemotherapy for BC. PURPOSE: To examine the effects of high-intensity interval training (HIIT) and moderate-intensity exercise training (MOD) on diastolic function following chemotherapy in women with breast cancer. METHODS: Twenty-four patients with BC scheduled to undergo chemotherapy were randomized to 1) HIIT or 2) MOD. Patients underwent 2D echocardiography (to assess diastology) and V̇O2peak testing 1-2 weeks prior to starting chemotherapy to establish peak HR (PHR) for exercise prescription. Exercise training began 1-2 weeks prior to treatment. HIIT consisted of 3-sessions/week of 4x4 minute intervals at 85%-95% PHR interspersed with 3-minute recovery intervals on a recumbent bicycle. MOD consisted of 150 minutes of walking at 70-75% PHR each week. The first 2 exercise sessions were supervised followed by remote monitoring for the rest of the study. Post-testing occurred within 3-10 days after the last treatment. After assessing for normality, between group differences in deltas was compared using an independent samples t-test, within-group differences were assessed with a paired t-test and α set at 0.05. RESULTS: Fifteen patients completed all aspects of the study (HIIT: n = 7, 55.3 ± 11.9 yrs, 78.7 ± 15.0 kg, 28.9 ± 5.5 kg/m2 & MOD: n = 8, 52.6 ± 11.2 yrs, 67.2 ± 9.1 kg, 26.0 ± 4.9 kg/m2). No significant changes were observed in E/e’, e’, E/A, and DT in the MOD group. In the HIIT group, a significant decrease in e’ was observed (Pre: 9.99 ± 2.87, Post: 8.33 ± 1.92, p = 0.043, d = -1.1). A trend toward a significant decrease in E/A was observed (Pre: 1.37 ± 0.43, Post: 0.99 ± 0.33, p = 0.081, d = -0.79). There were no significant between-group differences in ∆E/e’, ∆e’, and ∆E/A. CONCLUSIONS: Patients in the HIIT group saw modest changes in e’ and E/A during breast cancer chemotherapy, while patients in the MOD group did not. Diastolic dysfunction grade and other markers of diastolic function were not adversely affected. The clinical significance of these changes remains unknown and remains to be compared to a non-exercise control group.